A standard method for making uranium metal is the reduction of UF.sub.4 with magnesium as a reducing agent. The high cost of such a process has directed efforts at alternatives. One alternative is the use of electrochemical methods similar to the Hall-Heroult process used in making aluminum. These approaches presented major difficulties.
First, the high density and low solubility of uranium oxides resulted in fouled cells that prevented metal coalescence. Also, less than 50% of recovered metal is from uranium oxides, the rest being from UF.sub.4 which not only must first undergo conversion from the UO.sub.2 form before electrolytic reduction, but also produces an undesirable CF.sub.4 waste gas emission. The efficiencies are low, rarely exceeding 30% and usually lower than 20% for production from UO.sub.2. Cell capabilities are low due to low current efficiencies and because the maximum current is limited by the "critical current density" that gives an "anode effect" when CF.sub.4 is produced. Finally, in order to maintain continuous operation at 1200.degree. C., consumed carbon anodes must be repeatedly replaced, a difficult and dangerous job.
Therefore there is a continuing need to develop new, safe and efficient process for making uranium metal.